1. For superparamagnetic materials, we often pay attenetion to the coercivity and remance magnetization, and these values are often equal to 0 or very close to 0.

2. Normally we always pay much attention to the supermagnetic materials with high magnetization. A typical range is 30-200 emu/g. We can not descirbe the values only with emu

3. Different volume or different materials or other effects may exhibit different saturation magnetization.

4. Yes, superparamagnetic materials are related with the volume of particle V. If the diameter of magnetic particle is less than a critical diameter, which is in nanometer range and is different for the magnetic materials with different anisotropy.

Saturation magnetization (Ms) is an intrinsic nature of materials. Some materials e.g. barium hexaferrite (BaFe12O19) has high saturation magnetization up to 72emu/g. Totally, ferrimagnetic and ferromagnetic materials have hysteresis loops, while superparamagnetic ones has not loop, no coercivity (Hc) and no remanence (Mr). Usually, when particle size drops down below 10 nm the material shows superparamagnetic behavior.

Reading below articles maybe helps you in this field:

Acta Materialia 48 (2000) 223-238.

Materials Letters 67 (2012) 379–382.

Thanks a billion for very helpful and beneficial comments 

For biomediacal applications, more that saturation magnetization, it is the low field susceptibility that matters. This is beacuse the force one can apply to a particle is proportional to the gradient of Zeeman energy (coupling of M with H) and in an uniform applied field the gradient is thus proportional to dM/dH, which is the magnetic susceptibility...normally H is small, that's why is the low field susceptibility that matters.

Maybe one should also mention that in general it takes a large applied field to reach the saturation of superparamagnetic particles. Displaying zero coercivity is not sufficient to tell that one material is superparamagnetic: it can appear also in ferromagnetic materials along a hard axis. Thus, it might be convenient to check the angular dependence of the magnetization and anisotropies, or to measure the response of an array of randomly oriented particles.

1. For superparamagnetic materials, we often pay attenetion to the coercivity and remance magnetization, and these values are often equal to 0 or very close to 0.

2. Normally we always pay much attention to the supermagnetic materials with high magnetization. A typical range is 30-200 emu/g. We can not descirbe the values only with emu

3. Different volume or different materials or other effects may exhibit different saturation magnetization.

4. Yes, superparamagnetic materials are related with the volume of particle V. If the diameter of magnetic particle is less than a critical diameter, which is in nanometer range and is different for the magnetic materials with different anisotropy.

5. Not really. If the nanoparticle is a ferromagnetic or ferrimagnetic material, you may find the superparamagnetic effect when the volume of the particle is quite small. But if not, it may be mainly a paramagnetic effect.

6. The saturation magnetization role of supermagnetic materials mainly determined by the saturation magnetization of bulk magnetic materials, but it is less than the saturation magnetization of the magnetic materials because of the thermal fluctuation or size effect or other effects.

7. Higher saturation magnetization may be better, but it is not the only key factor.

Keep in mind that superparamagnetism is not a "new" magnetic state: in bio-applications is more appropiate to speak about single magnetic domain particles or multidomain particles. Superpara is just a manifestation of the finite character of the magnetic energy in sufficiently small particles. In AC applications the concept of superparamagnetism is completely doubtful, what is relevant is the time it takes for the magnetization to relax or to switch spontaneously between different energy minima

Paramagnetism is observed on atoms, molecules and lattice defects where their electrons have net magnetic moment.. At H=0, the orientations of magnetic moments are randomly distributed, and averaged to give "zero" value for any macroscopic magnetization measurement. When H is applied, the magnetic moments align towards the direction of the applied field; their magnetization linearly increases with the applied field. In one statement, they have no coercive field neither exhibit hysteresis behavior.

Unlike paramagnets, the net magnetic moments of electrons in ferromagnetic materials are spontaneously aligned owing to exchange interaction, thereby giving net magnetization even at H=0. They have non-zero coercieve field. They also exhibit hysteresis behavior because to rotate their magnetization from the preferred alignment (effective anisotropy direction K) to the direction of external magnetic field costs an amount of energy = KV, where V is the volume. 

Having said that, SuperParamagnetic Materials (SPM) are ferromagnetic materials, but due to their small size, the anisotropy energy KV becomes comparable to thermal energy kBT. As a result, at RT, the magnetization alignment in SPMs freely wander in the absence of external field (H=0). Hence, for any magnetization measurement, whose data acquisition time

The sample is superparamagnetic when the curves M(H), taken at different temperatures, coincide in coordinates (x=H/T, y=M).  This is expected behavior for ordinary paramagnets, nicely described by classic Langevien theory. So why superparamagnets?  This is because the initial slope of (normalized) curves M(H/T) (i.e. at H/T near zero) carry the information about the magnetic moment of a single magnetic ion.  When this slope is much too high to be attributed to a single ion as a "magnetic carrier", then we speak about superparamagnetism.  If this is the case, then "magnetic carrier" must be something else then the individual ion; it may be a molecule, a cluster of ions/molecules, or a grain of nanopowder, roughly speaking. When all magnetic particles in a sample are of the same shape and size then the curve M(H/T) strictly follows the Langevien formula.  Otherwise it is a composition of many similar curves.

You may be interested in my paper, dealing with decomposition of such a curve:

https://www.researchgate.net/publication/216481584_Langevin_granulometry_of_the_particle_size_distribution

Article Langevin granulometry of the particle size distribution

Superparamagnetism is driven by coercetivity force, temperature and grain volumen, they influence the relaxation time. So, superparamagnetism is not only a material property, a grain that is SP at a temperatura can be Single Domain (SD) at a a lower temperature. On the other hand remember that you always have a distribution of grain sizes, that usualy follow a log-normal distribution.

Beautiful explanation is given in "Introduction to Solid State Physics by Charles Kittel, Seventh Edition on page 477. It is so well written that I am unable to say more.

Hi, By the definition superparamegnetic state is related to coercivity. When you have Ferromagnetic and/or Ferrimagnetic particles with no coercivity, you have superparamagnetic state. Then for an ensemble of single domain particles at each temperature there is a critical size at which there is not coercivity (Hc=0). This is critical size of superparamagnetism. On the other hand for an ensemble of nanoparticles with definite size, there is a temperature (Blocking temperature TB) at that and temperatures higher than that (of course below Curie temperature) you have no coercivity, then you have superparamagneitc particles.

For saturation magnetization there is a model, named core-shell, that explains why saturation magnetization decrease with deceasing size. Based on this model saturation magnetization of nanoparticles is related to size directly. Then as you reduce particle size, you get lower magnetization.

Saturation magnetization of the nanoparticles depends on applications, but if you could prepare nanoparticles with a high saturation magnetization is a good situation, because reduction of it is simple!

Superparamagnetism is a unique feature of magnetic nanosized particles (HC = 0, MR = 0). The magnetic properties of the nanosize particles depend on the energy barriers, measuring time and relaxation time (The inverse spin-flip frequency). Ferromagnetic materials of a few nanometers become unstable when the energy barrier to magnetic reversal is comparable to kBT due to thermal excitation. Therefore, the material behaves like a paramagnetic macro-spin. This behavior is explained on the basis of the Stoner-Wohlfarth model of single-domain nanoparticles. The theory assumes an ensemble consisting of widely spaced, isolated, non-interacting single-domain particles with a coherent rotation of the magnetization of each particle. Superparamagnetic properties are influenced by the magnetocrystalline anisotropy which is caused by the spin-orbit (L-S) coupling in a crystal.

Jacob and Bean first gave theory of SP-materials. This is the state of either ferromagnetic or ferrimagnetic materials. When size of these materials is below certain range ( typically in range of few nanometers to few tenth of nanometers) then magnetic moment of the particle will be saturated and will be combined magnetic moments of all the atoms of the particle. It is a single domain state. For bio-applications one can select suitable size according to the type of application. If application involves protein then your size should be in the range of 5-50 nm etc. Usually , such nanoparticles exhibit preferential direction of alignment of magnetic moment. For one such direction the particle is referred as uniaxial anisotropic particle. Due to Brownian motion this direction flips and relaxation time for such flipping called Neel relaxation time is given by: τN = τoexp (∆E/κBT). Now a measurement technique has its own relaxation time τm. If (i) τm

Dear Rozita, for one type of nanoparticles take two different amounts of powder and make two measured M-H and see the result. You will obtain two saturation magnetization (in emu).

Is that possible ???

So I repeat.

Magnetic moment in emu is not relevant at all, to compare samples between them M must be expressed  in emu/g or emu/cm3

As stated clearly by several scientists the SP state is characterized by zero coercivity and remnant magnetization for a ferro- or ferrimagnetic material. SP behavior for a given granular sample with a specific particle size distribution is, however, observed above the "blocking temperature" for a system of single-domain particles; below this temperature the particles are blocked, and the sample exhibits coercivity and remnance (and is therefore not SP in this temperature range below the blocking temperature). As mentioned in earlier responses, the magnetic moment (in emu) is not characteristic of the sample; the magnetization (in emu/g or emu/cm3) is used to characterize the magnetic properties of the sample (among other magnetic quantities of course). Probably the unit stated in the original question was just a misprint. 

The saturation magnetization is characteristic of a bulk magnetic material. In a particulate system, however, the presence of a non-magnetic "dead layer" coating the magnetic core could reduce the saturation magnetization. The magnetization therefore is expected to decrease with decreasing the particle size, as the relative mass of material in the dead layer increases with decreasing particle size. The saturation magnetization of the particulate system was also reported to be dependent on the packing fraction of the magnetic particles in the sample.

The values of 1 and 60 (if these values represent magnetization rather than magnetic moment of the sample) stated in the original question are too far away from each other to represent the same material. Are these magnetizations obtained for nanoparticles of the same magnetic material? If not then the difference is understandable as being due to different magnetic properties of different materials. If the samples are of the same material then the difference is surprisingly large, and one should be concerned with the preparation methods of the two samples. For example, magnetic fluids prepared from fine particle suspensions of the same material exhibit different magnetization depending on the carrier type, the particle coating, and the fraction of the magnetic particles.    

Plz someone help me to solve VSM data

For superparamagnetic materials, we focus firstly on the values of coercive field (Hc) and remance magnetization (Mr) that should be very very very close to zero. Second point, you should determine mass magnetization (emu/g) or volume magnetization (emu/cm3) and not only emu (is not characteristic of the sample). Generally, Ms is preferable to be above 30 emu/g for applications. Also, the magnetization generally is expected to decrease with decreasing the particle size.